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How to connect to data on S3 using Pandas

This guide will help you connect to your data stored on AWS S3 using Pandas. This will allow you to validate and explore your data.

Prerequisites: This how-to guide assumes you have:
  • Completed the Getting Started Tutorial
  • Have a working installation of Great Expectations
  • Have access to data on an AWS S3 bucket

Steps#

1. Choose how to run the code in this guide#

Get an environment to run the code in this guide. Please choose an option below.

If you use the Great Expectations CLI, run this command to automatically generate a pre-configured Jupyter Notebook. Then you can follow along in the YAML-based workflow below:

great_expectations --v3-api datasource new

2. Instantiate your project's DataContext#

Import these necessary packages and modules.

from ruamel import yaml
import great_expectations as gefrom great_expectations.core.batch import Batch, BatchRequest, RuntimeBatchRequest

Load your DataContext into memory using the get_context() method.

context = ge.get_context()

3. Configure your Datasource#

Using this example configuration, add in your S3 bucket and path to a directory that contains some of your data:

datasource_yaml = fr"""name: my_s3_datasourceclass_name: Datasourceexecution_engine:    class_name: PandasExecutionEnginedata_connectors:    default_runtime_data_connector_name:        class_name: RuntimeDataConnector        batch_identifiers:            - default_identifier_name    default_inferred_data_connector_name:        class_name: InferredAssetS3DataConnector        bucket: <YOUR_S3_BUCKET_HERE>        prefix: <BUCKET_PATH_TO_DATA>        default_regex:            pattern: (.*)\.csv            group_names:                - data_asset_name"""

Run this code to test your configuration.

context.test_yaml_config(datasource_yaml)

If you specified an S3 path containing CSV files you will see them listed as Available data_asset_names in the output of test_yaml_config().

Feel free to adjust your configuration and re-run test_yaml_config() as needed.

4. Save the Datasource configuration to your DataContext#

Save the configuration into your DataContext by using the add_datasource() function.

context.add_datasource(**yaml.load(datasource_yaml))

5. Test your new Datasource#

Verify your new Datasource by loading data from it into a Validator using a BatchRequest.

Add the S3 path to your CSV in the path key under runtime_parameters in your BatchRequest.

# Here is a RuntimeBatchRequest using a path to a single CSV filebatch_request = RuntimeBatchRequest(    datasource_name="my_s3_datasource",    data_connector_name="default_runtime_data_connector_name",    data_asset_name="<YOUR_MEANGINGFUL_NAME>",  # this can be anything that identifies this data_asset for you    runtime_parameters={"path": "<PATH_TO_YOUR_DATA_HERE>"},  # Add your S3 path here.    batch_identifiers={"default_identifier_name": "default_identifier"},)

Then load data into the Validator.

context.create_expectation_suite(    expectation_suite_name="test_suite", overwrite_existing=True)validator = context.get_validator(    batch_request=batch_request, expectation_suite_name="test_suite")print(validator.head())

πŸš€πŸš€ Congratulations! πŸš€πŸš€ You successfully connected Great Expectations with your data.

Additional Notes#

If you are working with nonstandard CSVs, read one of these guides:

To view the full scripts used in this page, see them on GitHub:

Next Steps#

Now that you've connected to your data, you'll want to work on these core skills: